MARCO POLO SURFACE SCOUT (MASCOT) - STUDY OF AN ASTEROID LANDER FOR THE MARCO POLO MISSION

摘要

Marco Polo is being studied in the ESA Cosmic Vision programme as a sample return mission to a near-Earth asteroid (NEO) with participation by JAXA, with launch planned in the 2018-19 timeframe. In reponse to ESA's Declaration of Interest call in 2008, the Institute of Space Systems of the German Aerospace Center (DLR) led a proposal for a separate lander 'MASCOT' (Marco Polo Surface Scout) to be carried on the mission. The proposal was recommended by ESA for a feasibility study which was subsequently carried out from late 2008 to September 2009. In parallel to the Marco Polo flight opportunity, MASCOT was studied for the Hayabusa-2 mission currently studied by JAXA as the immediate successor to the currently flying Hayabusa mission. Launch would be earlier, taking place in 2014. The MASCOT study started with a preliminary assessment of lander type, landing mode, mobility options and their impact on minimum achievable mass and volume. Differentiation was made between legged landers ('landing in a defined orientation'), landing packages ('landing with uncontrolled orientation') and the number of achievable landing sites (single vs. multiple) and thus the degree of mobility. The analysis showed that a legged lander in the mass range of 70 kg-100 kg - with full mobility -, a weeks-long lifetime and ～14 kg P/L is feasible, given the weak gravity of potential target NEOs. Reducing size and capability, a legged lander of 30-40 kg was then conceived by giving up mobility, reducing lifetime and by cutting the P/L to ～10 kg. Finally, a mobile package version with an uprighting mechanism ('MASCOT-XS') and 3 kg of P/L was found feasible for a total mass of 10-15 kg. The constraints imposed by both the Marco Polo and Hayabusa-2 missions mandate MASCOT-XS to be the baseline for the MASCOT design.